There are a number of interesting extrasolar planet websites. In particular, NASA has a nice website called PlanetQuest that links to the various NASA plans for discovering exoplanets. They provide a particularly helpful summary of the four basic methods of finding planets that are currently in use (Doppler shifts, astrometry, transits, and microlensing). Geoffrey Marcy and Paul Butler, two of the leading planet searchers, maintain the Exoplanets website which includes lots of useful information, including a detailed description of the Doppler shift technique.
The microlensing technique is summarized here and here - this method has recently achieved success. The basics of the transit search method are described here. This method was originally used on a planet initially discovered by the Doppler shift method, and failed when used on a dense star cluster. Subsequently, however, this method also proved successful, and recently a project to look for transits toward the galactic center has proved quite successful.
Here is some information about the planets in our own solar system, and here are some pictures and information about NASA's programs to explore the solar system.